This application relates to new and useful improvements in methods and apparatus for testing and calibrating D.C. defibrillators.
It is standard practice to measure the energy output of a defibrillator discharged into a standard 50 ohm resistance. This has been done by measuring the voltage and current or just the voltage across the standard test resistance and then calculating energy from the relationship. ##EQU1##
Historically, these measurements were made by the use of oscilloscopes which were photographed, and measurements and calculations were then performed manually or by means of a calculator. Alternatively, measurements and calculations can be made using a digital computer.
Recently, several self-contained devices for measuring defibrillator energy have become commercially available. These devices simply were analog circuit implementations of the calculation equation and they were economically possible when integrated-circuit multipliers became available at reasonable prices which permitted the calculation of E.sup.2 in order to calculate the energy.
Other methods of indicating energy output are the use of a resistance network and neon lamp to flash at a predetermined voltage. Many previous attempts at measuring the energy output included a common error which was to misinterpret the energy equation by integrating and then squaring the signal. While this method can be scaled to read energy for a particular waveshape, it is not suitable for any variation from that shape and so is not suitable as a general purpose method.